This invention relates to medical monitoring systems and methods. In particular, a biomedical system and method for monitoring a patient is provided.
Biomedical monitoring systems include bedside, transportable, ambulatory and discrete vital sign monitors. In vital signs monitors, electrocardiograph (ECG), temperature, blood pressure or other characteristics of a patient are monitored.
ECG systems are used for monitoring activity of a patient's heart. For example, three electrodes are positioned on the patient. The signal from one electrode is used as a reference signal for a difference between the signals of two other electrodes (e.g. ECG vector). By using this reference signal, and a differential amplifier configuration, common mode interference can be essentially eliminated or reduced. As another example, nine electrodes are positioned on the patient for a “12-lead” analysis of electrical activity of the heart.
Wires are connected from the electrodes to an ECG monitor. The ECG monitor processes the signals and outputs ECG data, such as a plurality of traces representing activity of the heart by measuring electrical signals at different positions on the patient. However, the wires inhibit movement by and around the patient. The wires will stress the electrodes, resulting in malfunction or disconnection from the patient. A caregiver's time is then required to reconnect or replace the electrodes. Patients are often moved during a day, requiring disconnecting one ECG monitor and reconnecting another ECG monitor. Often the electrodes also need to be removed and replaced. If not replaced in exactly the same position, the patient's ECG will be different from ECG monitor to ECG monitor, creating an artifact in the ECG.
Wireless ECG systems connect the electrodes to a transmitter to avoid wires from the patient to a monitor. In the example described in WO 94/01039, a microchip is positioned proximate the electrodes on the patient. The microchip analyzes the signals from the electrodes and transmits the results (see page 42). The results are received and provided to a printer or monitor (see page 26). However, a complete system including a monitor, printer or recorder operable to receive the signals as processed by the microchip on the patient is required.
Holter monitors record a patient's vital signs over a time period. The patient carries the complete monitor and recorder. The information can be downloaded or otherwise obtained for subsequent analysis. However, many of these systems limit the bandwidth of signals to suppress artifacts associated with patient movement, so information can be lost. Special monitors or other devices may be required for obtaining the stored data for analysis, preventing maximum use of other equipment.
Wireless ECG systems often use patches or strips for positioning electrodes. The strip is fabricated with a plurality of electrodes electrically connected to the transmitter. If one electrode fails, the entire strip is replaced.